Materials exhibit deformation in response to a force. The amount of force necessary to generate a specific deformation, the speed of deformation at a specific position between undeformed and maximally deformed position, the onset of plastic deformation, are just three of many parameters that may characterize deformation response of a test object. Depending on the specific test object, other parameters, such as electrical resistance in the case of force activated electrical switch domes (which may be pressed by an operator to input data and may be found in a variety of electrical appliances and devices) may reveal valuable information about its switch-related functionality (e.g., will it function as a switch after 1,000,000 cycles?). Deformation force vs. deformation position (also referred to as displacement, or travel in the industry) information may provide information relevant to the functionality, suitability and/or applicability of a variety of test objects, whether they be materials, devices, contiguities, etc.
A classic example of an apparatus adapted to test performance is switch dome testers, which may be adapted to test force vs. displacement (or deformation position), electrical response, or life cycle response in order to characterize functionality, suitability and/or applicability of existing or intended switch designs. The most predominant type of such tester include strain gauges established in a cantilevered bar adapted to exhibit an enhanced deformation (due to vacuations established at non-terminal portions of the cantilever) in response to a load applied at one end. A deformation drive is supplied at a non-terminal site of the cantilever such that the strain gauges are between such non-terminal site and that site from which a “finger” that delivers a deformation force to the dome below is located. Electrical readings from such gages can then be used to generate force vs. displacement (also known as travel or deformation or simply position) data. Notably, such apparatus do not adjust an input to meet a constraint, do not exhibit a drive component and force deliverer that move simultaneously at the same speed and acceleration, and do not use a linear actuator in any fashion. Further, such apparatus may be limited in applicability, accuracy, reliability, durability, cyclical speed, controllability and/or range of applied force.
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that, with an enhanced (relative to prior art apparatus and methods) delivered force range and cyclical speed may have application not only in the field of switch dome testing but also in the field of testing for elastic response and hardness. Such enhanced ranges and speeds (e.g., in cycles per second and/or deformation speed) may be the result of the use of a voice coil based linear actuator. Indeed, embodiments of the inventive technology afford significant increases in cycles per second for reliability/life/cyclical response testing (greater than about 10 cycles per second, between about 10 to about 20 cycles per second, about 20 cycles per second, and, in certain embodiments, perhaps greater than about 20 cycles per second or more).
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that relies on an input-based control scheme, thereby affording an enhanced level of control and one that, in particular embodiments, is more suited to certain types of testing, particularly those where accelerative and inertial effects may introduce error to test results.
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that exhibits improved ability to recreate a test over several actuation cycles on different test objects (e.g., different force activated switch domes, or buttons).
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that exhibits improved accuracy in control of testing parameters, particularly over many deformations (e.g., 100,000 cycles), and, in certain embodiments provide control sufficient to replicate actual deformation force characteristics (e.g., speed, acceleration, force) to improve characterization of response, whether in singular force application or cyclic testing mode.
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that exhibits an improved ability to quantify reliability (e.g., the number of cycles until switch failure) of a test object designed to undergo cyclical deformation (e.g., a force activated switch dome).
It is a goal of at least one embodiment of the inventive technology to provide an apparatus and method that exhibits an improved ability to test mechanical response (mechanical decay) and electrical response (electrical decay) of, e.g., force activated switch domes, over repeated cyclic actuations.
Of course, other objects and advantages of the inventive technology may be disclosed in the sections that follow.